Physical and Chemical Properties of Water

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Questions and Answers

What is the main component of pure water?

Oxygen and nitrogen

Hydrogen and carbon

Oxygen and hydrogen (correct)

Nitrogen and carbon

At what temperature does water transition from liquid to solid?

50°F

100°C

32°F

0°C (correct)

What defines freshwater in terms of salt content?

More than 2% salt

Between 1% and 2% salt

Less than 3% salt

Less than 1% salt (correct)

Which of the following is a characteristic of saltwater?

Composed of at least 3% salt Signup and view all the answers

What is a common physical state of water at temperatures above 100°C?

Gas Signup and view all the answers

Which organisms are typically found in saltwater environments?

Sharks and tuna Signup and view all the answers

What is one of the critical roles of water in chemical reactions?

It acts as a catalyst Signup and view all the answers

How does saltwater density compare to that of freshwater?

Saltwater has higher density than freshwater Signup and view all the answers

What is the primary reason distilled water becomes corrosive over time in cooling systems?

It absorbs carbon dioxide from the air. Signup and view all the answers

Which type of water is NOT recommended for use in cooling systems due to high levels of contamination and corrosiveness?

Rainwater Signup and view all the answers

What is one of the severe risks associated with using sea water in engine cooling systems?

Severe corrosion and deposits formation Signup and view all the answers

Which of the following forms of corrosion is NOT typically associated with cooling water systems?

Oxidation corrosion Signup and view all the answers

What role do corrosion inhibitors play in cooling water?

They reduce the corrosive effects of distilled water. Signup and view all the answers

How does scale affect cooling water systems?

It leads to insulation and interferes with heat transfer. Signup and view all the answers

What is a key characteristic of pitting corrosion?

It creates small, localized holes that can lead to failure. Signup and view all the answers

Why is untreated tap water specifically discouraged in cooling systems?

It can lead to chalk deposit formation. Signup and view all the answers

What is the percentage of sodium chloride present in seawater?

79% Signup and view all the answers

Which of the following salts in seawater has the lowest amount in one kilogram?

Magnesium bromide Signup and view all the answers

What is the primary purpose of the cooling system on ships?

To remove unusable heat Signup and view all the answers

Which ion is most prevalent in seawater based on the provided data?

Chloride (Cl-) Signup and view all the answers

What is the amount of calcium carbonate found in one kilogram of seawater?

0.12 gm Signup and view all the answers

Which salt has a higher PPM in freshwater samples compared to seawater samples?

Sodium nitrate Signup and view all the answers

What is the role of the cooling liquid in the marine engine's cooling system?

To cool the engine components Signup and view all the answers

Which of the following contributes the least to the overall PPM of dissolved solids in seawater?

Calcium bicarbonate Signup and view all the answers

What is the primary risk associated with using galvanized piping in a diesel cooling system?

Temperature-induced corrosion of zinc Signup and view all the answers

Before applying corrosion inhibitors, what is recommended for the zinc galvanizing?

Removing it through acid treatment Signup and view all the answers

Which chemical is specified as a corrosion inhibitor protective to cast iron, steel, and aluminum?

Sodium Nitrite Signup and view all the answers

What is the recommended dosage range for Sodium Benzoate as a corrosion inhibitor?

10000 to 15000 ppm Signup and view all the answers

Which of the following inhibitors is known to provide some alkalinity by buffering at a pH of 8.9?

Sodium Borate Signup and view all the answers

What must be tested in the cooling water to determine the proper concentration of inhibitors needed?

Chloride or sulfate concentration Signup and view all the answers

Which inhibitor is used for protection against corrosion specifically in copper and copper alloys?

Sodium Borate Signup and view all the answers

Which of the following statements is true regarding the use of Zinc in cooling systems?

Zinc acts as a protective sacrificial metal. Signup and view all the answers

What should be done if deposits or rust are detected in a cooling water system?

Conduct a thorough cleaning and refill with newly treated water Signup and view all the answers

Which procedures are included in the cleaning of a cooling water system?

Degreasing and descaling procedures Signup and view all the answers

Who is recommended to carry out the cleaning of the cooling water system?

A reliable specialist firm Signup and view all the answers

What should you do if a specialist firm is not available for cleaning the cooling water system?

Follow instructions from the supplier of cleaning chemicals Signup and view all the answers

What is a key reason for cleaning the cooling water system?

To maintain system efficiency and prevent damage Signup and view all the answers

What characteristic of the cleaning chemicals used in the cooling water system requires caution?

They may be hazardous Signup and view all the answers

What happens to the cooling water after cleaning the system?

It should be completely refilled with newly treated water Signup and view all the answers

Why is it important to follow specific instructions when cleaning the cooling water system?

To ensure safe handling of potentially hazardous chemicals Signup and view all the answers

Study Notes

Water Chemistry Overview

Water is a clear, colorless liquid composed of two hydrogen atoms and one oxygen atom (H2O).
Covers over 70% of the Earth's surface and is essential for life.
Exists in three phases: solid (ice, ≤ 0°C), liquid (0°C to 100°C), vapor (≥ 100°C).
Boiling point: 100°C (212°F); Freezing point: 0°C (32°F).

Freshwater vs. Saltwater

Freshwater: contains < 1% salt, found in lakes, streams, and glaciers; tasteless and odorless.
Saltwater: contains ≥ 3% salt, primarily in oceans; unsuitable for human consumption; home to marine organisms like sharks and tuna.

Composition of Seawater

Major components include Sodium Chloride (NaCl), Magnesium Chloride (MgCl2), and Magnesium Sulfate (MgSO4).
Sodium Chloride constitutes 79% of dissolved solids in seawater, with approximately 25,000 PPM concentration.
Common ions in seawater: Chloride (55.03%), Sodium (30.59%), Sulfate (7.68%).

Marine Engine Cooling Water System

Critical for ships to remove excess heat from engines and machinery.
Cooling achieved by circulating liquid around engine passages, preventing overheating and preserving metal properties.

Quality Requirements for Cooling Water

Best suited with demineralized (distilled) water; corrosion inhibitors necessary to prevent environmental corrosion.
Rainwater and tap water generally not recommended due to contamination and chalk deposits.
Sea water can cause severe corrosion and deposits, hence prohibited as cooling water.

Corrosion in Cooling Water Systems

Corrosion: degradation of materials through chemical or electrochemical reactions.
Common forms: general wastage, pitting, crevice, galvanic, stress, and erosion corrosion.
Corrosion can form insulating scale, impairing heat transfer.

Zinc Presence and Corrosion Management

Zinc galvanization used for protection against corrosion but may reverse polarity at high temperatures (60°C to 90°C), potentially increasing corrosion.
Recommended to remove galvanized elements before adding corrosion inhibitors.

Chemicals for Cooling Water Treatment

Sodium Nitrite (NaNO2): protects cast iron and steel, dosage 1000 to 3000 PPM.
Sodium Benzoate (C8H5CO2Na): protective for steel and solder, dosage 10,000 to 15,000 PPM.
Sodium Borate (Na2B4O7): offers alkalinity, buffers at pH 8.9, dosage 1000 to 3000 PPM.

Cleaning Cooling Water Systems

Abnormal deposits necessitate thorough cleaning and refilling with freshly treated water.
Cleaning involves degreasing and descaling using special chemicals; should be done by specialists following safety protocols.

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Description

This quiz covers the key aspects of the physical and chemical properties of cooling water as discussed in Topic 1 Lesson 2. You will explore water chemistry analyses, including the identification and quantification of chemical components. Understand the significance of pure water and its forms in various contexts.